Question

72.90 litres of mixture contains milk and water in the ratio 7:2 .How much more water must be added to this mixture so that the ratio of the milk and water may be 7:3.
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Answer 1

The ratio of milk and water in the mixed liquid of 72.90 liters is 7:2. How much more water must be added so as to make the ratio 7:3?

ANSWER :

Add x litres of water to make the ratio 7:3.

Initially there were 7x litres of milk and 2x litres, or

7x+2x = 72.90, or

9x = 72.9, or

x = 8.1

So the milk was 56.7 litres to 16.2 litres water.

Now add w liters of water to the mixture to get

56.7 litres (milk) and (16.2 +w) litres of water.

Now 56.7 : (16.2+w) = 7:3 or

3*56.7 = 170.1 = 7*16.2 + 7w, or

7w = 170.2–113.4 = 56.8, or

w = 56.8/7 = 8.11 litres.

So add 8.11 litres to the original to get the new milk to water ratio as 7:3.